Preparation of hydroxy-carboxylicacids



Patented Mar. 4, 1952 UNITED STATES PATENT OFFICE PREPARATION OF HYDROXY-CARBOXYLIC- ACIDS No Drawing. Application November 17, 1949, Serial No. 128,024. In Germany October 20, 1948 This invention relates to the production of polyhydroxymonocarboxylic acids and more particularly to a catalytic process for the oxidation of sugars.

It is known that the oxidation of reducing sugars with oxygen or air in an alkaline solu- 1 tion can be carried out in such a manner that a polyhydroxymonocarboxylic acid having one less carbon atom, is obtained as the chief reaction 14 Claims. (Cl. 260-528) The following example serves to illustrate the action of the catalysts of this invention:

150 grams of saccharose are dissolved in 1200 cos. of water, the solution obtained is inverted after the addition of some hydrochloric acid and thereupon filled into a glass tube of 75 mm. diameter. Oxygen is introduced from below in a vigorous current through a clay filter candle. From a dropping funnel a solution of 147.5 grams product. For this purpose, oxygen or air in very in of caustic potash in 950 cos. of water is added fi y distributed form s u d to react p by' drops within 2 hours. The temperature rises" the monosaccharides in an alkaline solution. spontaneously and is then kept at 40-42 G. Since the yield obtained according to the above Oxygen is passed through for another 2 hours process s satisfactory I have made efforts to and then air for a further 4 hours. The progress flu the a n by adding atalysts. A1-. 15 of the oxidation can be tested, for instance, by ou h the usual catalysts, e. m tals, par y a titration. After completion of the oxidation the celerate the oxidation process they have proved working up may be ied t a follow n to promote h r i n f. p lyhydr xy- The solution is neutralized with glacial acetic monocarboxylic acids but to influence the oxidaacid and reduced in vacuo to a small volume. tion in a different direction 20 The potassium arabonate formed crystallizes. I have found that Certam creams For completing the precipitation methanol may pounds defimtely promote 15136 forfnatmn of p015" be added. The reaction product isolated by hydmxymonocarboxyhc aclds" licreismg sucking off and washing with methanol is dried; g of acigs fi reducing he g The following table gives a summary of the methylene blue is distinguished by an excellent i whilse dlfierent catalyticauy actlve catalytic action; also compounds of the oxazine s 1 t th t ts and phenazine series have proved to be opera- 0 Comp 6 e 6 compare" Ive es tive The addition f Small amounts of Such cording to the above schedule some of the experi- Substances sufijces t catalyze t oxidation ments listed in the following table were carried action in a manner such as to achi v sub tanout with air exclusively and some others with tial increases in the yield. oxygen exclusively.

Time of in- Yield of ara- Quantity of troducing bonatc of N0. Catalyst the catalyst potassium in used grams (theooxygen air ry 180 grams) hours hours a a s 96 Methylene blue tetramethyldiamino-diphenazo-thi- 4 4 148 onium chloride) Schultz No. 1038.

4 4 142.5 4 4 129 s 147 9..-- ...do lgram 8 140 10.-- Methylene green (tetramethyldiamino-nitro-dlphenlgram 4 4 129 azo-thionium chloride) Schultz No. 1040. 1 1--- Methylene violet (amino dimethylamlno-phenyl-dilgram 4 4 131 phenozonlum chloride) Schultz No. 959. 12.-- Thionine blue (trimethyl-ethyldiamino-dlphenazo- 1 gram 4 4 143 thionium chloride) Schultz No. 1042. 13... Lauths violet (diaminodi hcnazo-thionium chloride) 1 gram 4 4 126.5

Schultz No. 1036. 14- Celestine blue (diethylamino-dihydroxy-carboxy-dilgram 4 4 130 phenazoxoniuni chloride) Schultz No. 1021. 15--- Rosindullne GG (sodium salt of the azlne dye, rosln- 1 gram 4 4 127.6

done) Schultz No. 950.

' r 3 It follows from this table that on working in accordance with my invention the yield of polyhydroxymonocarboxylic acids is considerably increased. The best result is obtained by using methylene blue as catalyst. The eiiiciency of the catalyst is not only proved on using oxygen exclusively or on subsequently completing the oxidation with air but also on using air exclusively. This means a substantial economy in oxygen when working on a technical scale since a considerable part of the oxygen passes through unused. Without using catalysts yields are obtained with air which are far below those obtained with oxygen or with oxygen and air (of. tests 1, 2 and 3).

The melting points (with decomposition) of the products obtained according to the invention are between 215 and 220 C. On conversion into calcium arabonate good yields are obtained. Only a slight amount of insoluble calcium salt (calcium oxalate) is formed owing to the fact that the formation of by-products of the oxidation process is substantially reduced. Any adhering residues of catalysts as far as these have not been washed out with methanol can easily be removed, for instance, by means of animal charcoal.

For the purpose of comparison the tests enumerated in the above table have been carried out in the same manner. However, it is also feasible to vary the conditions of the oxidation and working up within a wide range, not only as to temperature, time, concentration etc. but also, for instance, as to the amount and kind of the alkali used.

I I claim:

1. In the process of oxidizing reducing sugars to yield the corresponding polyhydroxyrnonocarboxylic acids with one carbon atom less than the sugar employed with oxygen containing gases in an alkaline medium, the step which comprises adding to the solution of the sugar a compound selected from the group consisting of methylene blue and its analogs of the thiazine-, oxazine-, and phenazine-series.

2. In the process of oxidizing inverted saccharose to yield arabonic acid with oxygen containing gases in an alkaline medium, the step which comprises adding to the solution of said inverted saccharose a compound selected from the group consisting of methylene blue and its analogs of the thiazine-, oxazine-, and phenazine-series.

3. In the process of oxidizing inverted saccharose to yield arabonic acid with air in an alkaline medium, the step which comprises adding to the solution of said inverted saccharose a small amount of methylene blue.

5. In the process of oxidizing inverted saccharose to yield arabonic acid with oxygen in an alkaline medium, the step which comprises adding to the solution of said inverted saccharose a small amount of methylene blue.

6. In a process for the production of aliphatic polyhydroxymonocarboxylic acids by oxidation, with an oxygen-containing gas, of a reducing sugar with oxygen in an aqueous alkaline reaction medium, the improvement that comprises performing this oxidation while having present in the reaction medium, a catalytically effective amount of catalyst comprising a substance of the group consisting of methylene blue and its analogs of the thiazine, the oxazine and of the phenazine series.

A process as defined in claim'6 wherein the sugar is inverted sucrose and the catalyst is a thiazine dye.

8. A process as defined in claim 7 wherein the thiazine dye is methylene blue.

9. A process as defined in claim 7 wherein the thiazine dye is methylene green.

10. A process as defined in claim 7 wherein :the thiazine dye is methylene violet.

11. A process as defined in claim 6 wherein the.

sugar is inverted sucrose and the catalyst is an oxazine dye.

12. A process as defined in claim 11 wherein the oxazine dye is Celestine blue, Schultz No.

13. A process as defined in claim 6 wherein the sugar is inverted sucrose and the catalyst is a phenazine dye.

14. A process as defined in claim 13 wherei the phenazine dye is rosindulin'e.

HANS SCHMIDT.

. REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,190,377 Dalmer et a1 Feb. 13, 1940 2,207,738 Hudson et a1 July 16, 1940 FOREIGN PATEN Number Country Date R 618,164 7 Germany Sept. 3, 1935 620,248 Germany Oct. 17, 1935 OTHER REFERENCES Moruzzi, Chem. Abstracts, vol. 31, col. 8560 (1937). 

1. IN THE PROCESS OF OXIDIZING REDUCING SUGARS TO YIELD THE CORRESPONDING POLYHYDROXYMONOCARBOXYLIC ACIDS WITH ONE CARBON ATOM LESS THAN THE SUGAR EMPLOYED WITH OXYGEN CONTAINING GASES IN AN ALKALINE MEDIUM, THE STEP WHICH COMPRISES ADDING TO THE SOLUTION OF THE SUGAR A COMPOUND SELECTED FROM THE GROUP CONSISTING OF METHYLENE BLUE AND ITS ANALOGS OF THE THIAZINE-, OXAZINE-, AND PHENAZINE-SERIES. 